Gas checks have been in use in munitions since the 1800s. Application of gas checks ranges from use in artillery to pistol and rifle rounds. Gas checks serve many different purposes based on the particular application. In the case of monolithic solid brass/copper projectiles, gas checks are used to prevent buildup of excessive chamber pressures and allow these rounds to achieve velocities comparable to jacketed lead counterparts, while keeping pressures at or below Sporting Arms and Ammunition Manufacturers' Institute (“SAAMI”) maximums. In some instances, gas checks are formed as bands that protrude above the surface of the projectile. In other instances, gas checks are formed as rings in the surface of the projectile.
A commonly used form of gas check is a square-cut gas check, in which annular, square-edged grooves are cut or formed into the bearing surface of a projectile. Thus, leaving a series of cylindrical relief bands alternating with drive bands having the same outer diameter as the bearing surface of the projectile. One major drawback of square-cut gas checks is that the shape of the drive bands and relief bands on gas checks produces aerodynamic drag and turbulence. Indeed, in some instances, turbulence is created around the grooves and rings, as well as increased behind the bullet upon firing. See, for example, the simulated turbulence of a projectile 100A traveling at 2000 fps without a gas check compared to the turbulence behind a projectile 100B with a gas check having square-edged drive bands and relief bands on the bearing surface, in FIG. 1. Note the increased turbulence around and behind the projectile 100B.